In cylinders of internal combustion engines, intake airflow patterns can affect combustion characteristics such as efficiency, ignition, and knock. Intake airflow affects both port as well as direct injection fuel systems. Tumble and swirl patterns are used to characterize different aspects of the turbulence in the cylinder. Specifically, tumble and swirl ratios can be used to quantify the magnitude of these flow patterns. Tumble ratio is defined as the strength of horizontal recirculation of the intake gas in the cylinder while swirl ratio is defined as the strength of vertical recirculation in the cylinder. Tumble and swirl patterns have different influences on various facets of combustion such as ignition, knock, efficiency, emissions, power, etc. In previous engine's intake ports are designed to provide fixed tumble and swirl patterns that improve combustion only for a specific operating condition. Therefore, when the engine is operated over a wide range of conditions, the set patterns of the combustion airflow can negatively impact combustion when the engine is run outside of the specified operating condition.
To address at least some of the aforementioned problems, an engine system is provided. The engine system includes a rotatable flow guide including a flow altering surface positioned upstream of an intake valve having a first side with a curved contour, the flow altering surface generating tumble and swirl flow patterns of intake airflow entering a cylinder through the intake valve in a plurality of active positions. The engine system further includes a flow guide actuator rotating the flow altering surface to alter the tumble and swirl flow patterns of the intake airflow. In this way, the flow altering surface changes the turbulence of air entering the cylinder to improve combustion efficiency, reduce knock, increase power, and/or decrease emissions, across a wide range of operating conditions. Thus, the flow altering surface can be rotated to provide turbulence in the cylinder that best suits the current operating conditions, if desired.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.